The present invention relates to a compact elastomeric bladder infusion pump for administering a pharmaceutically active material at a substantially constant flow rate over the service cycle of the pump. More particularly, the present invention relates to an improved infusion pump having an internal stress member disposed within the bladder, which prestresses the bladder in both the axial and radial directions thereby enabling the bladder to exert a substantially constant pressure on the contents thereof throughout the service cycle. Although a variety of elastomeric bladder infusion pumps are known, there remains a need for an infusion pump which is simple and inexpensive from a manufacturing standpoint, yet is capable of delivering its contents at a substantially constant rate.
None of the prior art elastomeric bladder infusion pumps known to the inventor may be easily manufactured, at a low per-unit cost, yet exhibit a high degree of reliability in terms of storage life and the ability to deliver substantially all of the contents at a substantially constant flow rate.